Breast Anatomy

Breast comprised of

Fibrous tissue, glandular tissue, adipose tissue

Dense breast tissue

Fibrous tissue

Functional breast tissue

Glandular tissue

What type of gland is the breast

Mammary gland

Modified sweat gland

4 anatomic zones

Skin, nipple, subareolar structures

Subcutaneous region

Parenchyma (mammary region)

Retromammary region

Breast location

Anterior chest wall extending from second to sixth or seventh rib and the lateral border of the sternum into the axilla

Nipple

Central raised portion

Areola

Pigmented skin that surrounds the nipple

Montgomery glands

Located within the areola

(Bumps)

Tail of Spence

Tissue extending towards the axilla

Mammary milk line

Oblique line extending from axilla to symphysis pubis

What tissue provides support for breast

Stroma and subcutaneous tissue

What tissue is the central part of breast

Mostly glandular tissue

What tissue is the peripheral part of breast

Mostly adipose tissue rimmed by superficial fascia

3 layers

Subcutaneous

Mammary

Retromammary

Subcutaneous layer

Under the skin, very thin, composed of fat (adipose)

Separated by septae of connective tissue

Mammary layer

Majority of breast thickness, functional layer, fibroglandular/parenchymal layer

Retromammary layer

anterior to chest wall, very thin

Which layer is most of breast tissue located

Mammary layer

Glandular tissue

Contains 15-20 lobes, which produce milk; each lobe has a central duct with branches leading to acini

Ducts tissue

Ducts from each lobe carry milk to the nipple

What are Stromal elements

Supporting structures located between and within lobes

Stromal elements ex:

Dense and loose connective tissue

Fat

Coopers ligaments

Coopers ligaments

Connective tissue septae that form a fibrous skeleton within the breast

Terminal ductal lobar unit (TDLU)

Small units made up of terminal ducts and their acini

Suspended within the skeleton of coopers ligaments

What are TDLUs surrounded by

Loose and dense connective tissue

Site of origin of nearly all pathologic processes

Terminal ductal lobar unit

Male breast tissue

Nipple and areola remain same

Ductal tissue do not develop acini

Male breast tissue can develop:

Gynecomastia

Breast cancer

Infection

Where does blood flow to the chest originate

The subclavian and axillary artery

Blood flow to chest

Thoracic branches of axillary artery

Posterior intercostal branches of descending thoracic aorta

Internal mammary artery from subclavian

Mammary venous drainage

Veins form circular pathway around the areola, branches into the peripheral portions of the gland draining into the axillary and internal mammary veins

What is venous drainage supplied by

Superficial veins just under the skin that empty into tributaries of the subclavian vein

true or false: lymphatics of the breast communicate with each other

True

Breast lymphatics are continuous with the superficial lymphatics of:

The abdomen skin and neck

Breast lymphatics

Drain fat molecules in milk as they are generally too big for the veins

Transfer injection or malignancy from breast to more distant areas

3 major routes of lymphatic spread

Supraclavicular

Medial breast area

Axillary

Axillary lymph node chain

Accounts for 75% of lymphatic drainage of breast

Consists of 6 groups of nodes

6 groups of nodes in axillary lymph node chain

External mammary

Scapular

Axillary

Central

Subclavicular

interpectoral (rotter’s)

Axillary nodes

Located in armpit

Drain majority of breast tissue

Internal mammary chain lymphatics

Channel leads from one breast to the other

Inner quadrants drain via this route

Interpectoral lymph nodes

Rotter’s nodes

Between pectoral muscles

Supraclavicular nodes

Located along the subclavian vein near the clavicle

Upper quadrant drain via

Carries worst cancer prognosis

Parasternal nodes

Located along each side of sternum

Inner quadrants drain via

Inferior phrenic nodes

Inferior to diaphragm

Lower inner quadrants drain via

Breast function

Lactation- milk secretion and ejection

Milk secretion

Largely due to prolactin hormone from anterior pituitary

Prolactin

Chief hormone that causes the acinar cells to produce milk during lactation

Milk secretion influenced by

Progesterone and estrogen

Milk ejection

Occurs in presence of oxytocin from posterior pituitary

Released by stimulation of infant sucking

Development begins:

Before puberty and continues for first 2 years of menstrual cycle

What hormones have primary hormonal control over breast tissue

Estrogen and progesterone

Estrogen

Stimulates connective tissue; causes proliferation of ductal tissue

Progesterone

Stimulates glandular tissue (TDLU)

When do lobes and acini develop

At onset of ovulation

Is ultrasound or mammogram typically done first

Mammogram

Breast ultrasound when?

Lesion found on mammo

Mammo is indeterminate

Palpable lump

Axilla for lymphadenopathy

Procedure guidance

Reasons ultrasound would be used INSTEAD of mammogram

Patient is <30 and has palpable mass

Pregnant or lactating patients

Most common patient position

Supine

Skin line echogenicity

Highly Echogenic

Nipple US appearance

Hypoechoic with posterior shadowing

Subareolar US appearance

Posterior to nipple

Shows dilated, anechoic lactiferous ducts

Subcutaneous fat Us appearance

Hypoechoic

Retromammary layer US appearance

Hypoechoic

Coopers ligaments US appearance

Thin, linear, Echogenic

May cause shadowing

Duct US appearance

Anechoic tubular structures

Pectoral is major Us appearance

Low level echo areas

Ribs US appearance

Oval, Hypoechoic structures posterior to pectoral if major

Axillary vessels US appearance

Tubular, anechoic structures with color flow

Lymph node US appearance

Hypoechoic rim with Echogenic fatty hilum

Radial

Notch pointing toward the nipple

What clock times is the notch pointing towards the nipple in radial plane

1-6

What clock times is the notch pointing away from the nipple in radial plane

7-12

Which clock positions does the transducer notch flip in antiradial plane

4 and 10

Breast annotation should include

Laterality, right or left

Clockface position

Distance form nipple in cm

Transducer orientation, radial or antiradial

Standoff pad

Create distance between transducer and superficial layers of skin/breast to improve visualization of superficial masses

Fremitus maneuver

Use color or power Doppler

Used to distinguish borders of a mass

True mass not filled in with color

How to do fremitus maneuver

Locate suspicious mass

Turn down power setting

Place power or color box over mass

Have patient hum

Craniocaudal view (CC)

Compressed superior to inferior

Shows if lesion is medial or lateral

Medial lateral oblique (MLO) view

Compressed obliquely from side to side

Determine if lesion is more superior or inferior